Hy-Velocity

I have a 2000 HP500EFI in a 29 foot Velocity, the engine is stock except for Eddie Marine exhaust with the long stainless risers, it has a set of Canfield Alu. heads that have been CNC ported along with the combustion cambers,the heads have been milled .030 to bring the compression up to a little over 9 to 1, the CMU has be recalibrated by Tyler Crocket and it has a K&N flame arrestor. The port size is 319 if I remember right. The boat runs about 73 GPS now, would like to run close to 80 as most 29's Velocity's do with 525's in them.

Are the Eddie Marine exhaust hurting my performance that much as compared to the stock tube exhaust that comes on a HP 500 EFI. Do I need to try and find a set of these exhaust somewhere to replace my current set up?

The 2000 tech manual says the cam in the engine has: 211 degree duration intake and 227 degree duration exhaust with a .581 lift for both valves. Would a cam change be worth the time and money?

Any other recommendations from anyone other than a blower or supercharger. I do not want to go that rout yet. Thanks in advance for you help.

Dave M

I thought HP500EFI's came with CMI exhaust? If anything, they look much better that the Eddie Marines. Your speed sounds low. It sounds like you may not be putting out the 470HP that the 500's are rated at. I've read posts from other 29 Velocity owners that are going that fast with a 496HO.

Hy-Velocity

Thanks Dave for you response, I think that the HP 500 EFI engines do not come with exhaust on them, you have to purchase them extra. At least mind didn't come with exhaust.

Strip Poker 388

I was thinking the first 500efi's came with the gils????? like the carb hp 500's

After that they came with the CMI's

JaayTeee

500 EFI cam specs are
230*/236*
.598/.610"

I'd be looking at the exhaust.

Pat McPherson

If you're running the stock HP500EFI cam, I would not think the ECU would need to be recalibrated with just better flowing heads and a small bump in compression. You may want to ask Tyler if just a little more fuel pressure would be a better way to go.
The headers would help some but I'd also be looking at other areas of your setup.
What kind of prop slip #s are you seeing?
To run close to 80, you will need like 5200+ motor rpm, 28p+ prop, 1.5 drive.

Hy-Velocity

Jay thanks for the response, but the 2000 HP 500 EFI tech manual I have says that the cam specs are as written above.
Maybe the carbed engines have this cam or the older engines. I am really confused now.

Hy-Velocity

Pat the prop is a out of the box bravo 28 pitch with a 1.5 outdrive. The engine rpms' are about 5100 to 5200 with the speedo say around 77 to 78 and the GPS at 73.6. I thinks this is slow for this set up.

Pat McPherson

The slip is a bit high but not horrible. Have you asked others that have your boat what prop they run?

Also, I edited my post. Did you get that part about the ECU?
I had an ECU reprogrammed 3 times and the stock calibration was still the best on my modified engine...
If the calibration is not done on a dyno, it's a crap shoot.

Hy-Velocity

I will give Tyler a call and see if maybe the stock settings other than the RPM limiter should be reprogramed back into the computer, the engine stumbles and runs rough between 1200 rpm and 2000 rpm, after that it cleans itself out and runs fine. The CMU might be the problem. Other 29 Velocity's with 525's are all running 27 pitch, 5 blade Hydro. props and are running 82 to 83 GPS @ 5200 rpm.